The reason why we have to call the Spruces Picea, and not Abies, and the Firs Abies, and not Picea, is thus given by Dr. Engelmann in his recent monograph on the Firs of the United States:

" I follow Link (Linnoea, xv., 525, 1841) in his name, definition, and circumscription of the genus, which seems to be a very natural one, comprising the Silver or Balsam Firs. The synonym Picea (Don) in Loudon, Arb., iv., 2329, 1838, is the older name, and enjoys the Linnaean prestige, (but is contrary to classical Plinius, etc.,) and philological authority. The name Abies is generally adopted on the continent of Europe, while Picea was heretofore principally used in England, but is now being abandoned. Picea, Link (the same Abies, Don), is the proper name for the Spruces. Tournefort, the elder De Candolle, Gray, and others, comprise under the name of Abies both Firs and Spruces. The generic distinctions between them are based both on the floral and fruit characters, as well as on the leaf anatomy".